Performance sound of multiple musical instruments playing one musical composition may be recorded for each of the musical instruments independently in a live performance or the like. In this case, the recorded sound of each of the musical instruments is composed of mixed sound in which performance sound of each of the musical instruments is mixed with performance sound of the other musical instruments called “leakage sound.” When the recorded sound of each of the musical instruments is processed (for example, delayed), the presence of leakage sound may become problem, and it is desired to remove such leakage sound from the recorded sound.
Also, sound recorded with a microphone generally includes original sound and its reverberation components (reverberant sound). Several technical methods have been proposed to attempt to remove reverberant sound from mixed sound in which original sound is mixed with the reverberant sound. For example, according to one of such methods, a waveform of pseudo reverberant sound corresponding to reverberant sound is generated, and the waveform of the pseudo reverberant sound is deducted from the original mixed sound on the time axis (for example, see Japanese Laid-open Patent Application HEI 07-154306). According to another method, a phase-inverted wave of reverberant sound is generated from mixed sound, and is emanated from an auxiliary speaker to be mixed with the mixed sound in a real field, thereby cancelling out the reverberant sound (see, for example, Japanese Laid-open Patent Application HEI 06-062499).
However, with methods as described in Japanese Laid-open Patent Application HEI 07-154306, the sound quality of the reproduced sound can be poor, unless waveforms of the pseudo reverberant sound are accurately generated. With methods as described in Japanese Laid-open Patent Application HEI 06-062499, audience positions where reverberant sound can be removed are limited.